General Electric AC4400CW

The AC4400CW is a 4,400-hp, six-axle road switcher introduced in 1994. Basically, it is a Dash 9-44CW, but with three-phase AC traction motors. Both were the last road switchers built for the domestic market which were powered by the 7FDL engine that had been introduced in the fifties. Compared to its DC counterpart, it produces a starting tractive effort of 180,000 pounds or 800 kN, instead of only 142,000 pounds or 631 kN. The standard variant weighs 426,000 pound or 193 metric tonnes and optionally, the weight could be increased with 20,000 pounds of ballast. An option offered with these locomotives were self-steering trucks, but these were not ordered by many customers.

Between 1994 and 2004, a total of 3,018 AC4400CW were delivered to North American railroads. The largest customer was Union Pacific with 1,169, followed by CSX and by Canadian Pacific/Kansas City Southern with more than 500 each. At the same time, GE offered the more powerful AC6000CW that suffered from reliability issues. In North America, the ES44AC with the new GEVO engine was introduced in 2003 due to new emissions regulations.

But between 2008 and 2022, a number of Brazilian customers received a total of 540 similar locomotives in broad gauge which were designated AC44i and were still powered by the 7FDL. From the mid-2010s, the first AC4400CW in North America were rebuilt by some railroads. Among the changes were more modern traction electronics for more pulling power, improvements in fuel efficiency, an increased reliability and more modern cab equipment.